PSLE Albert had silver pens and red pens for sale. He sold 100 silver pens. 60% of the pens sold were red.
- How many silver pens and red pens did Albert sell altogether?
- He sold 50% of his pens. 70% of the pens left unsold were silver. How many red pens did Albert have at first?
| |
Silver |
Red |
Total |
Total in percent |
| Before |
5.5 u |
4.5 u |
10 u |
100% |
| Change |
- 40%
- 2 u |
- 60%
- 3 u |
- 100%
- 5 u |
- 50% |
| After |
70%
3.5 u |
30%
1.5 u |
100%
5 u |
50%
|
60% =
60100 =
35 Total number of pens sold = 5 u
Number of red pens sold = 3 u
Number of silver pens sold
= 5 u - 3 u
= 2 u
2 u = 100
1 u = 100 ÷ 2 = 50
Total number of pens sold
= 5 u
= 5 x 50
= 250
(b)
Percent of the pens left unsold = 100% - 50% = 50% 50% of the pens that were sold = 5 u 50% of the pens that were left unsold = 5 u Percent of the pens left unsold that were silver = 70%
Percent of the pens left unsold that were red = 100% - 70% = 30%
Number of the pens left unsold that were red
= 30% x 5 u
=
30100 x 5 u
= 1.5 u
Number of red pens that Albert had at first
= 1.5 u + 3 u
= 4.5 u
= 4.5 x 50
= 225
Answer(s): (a) 250; (b) 225
